Merge pull request #49 from BlaiseD/master

Fix InvalidOperationException mapping nested lambda expressions.  Fixes Issues #48.

Author: BlaiseD

Directory.Build.props

@@ -2,7 +2,7 @@
   <PropertyGroup>
     <Authors>Jimmy Bogard</Authors>
     <LangVersion>latest</LangVersion>
-    <VersionPrefix>3.0.3</VersionPrefix>
+    <VersionPrefix>3.0.4-preview01</VersionPrefix>
     <WarningsAsErrors>true</WarningsAsErrors>
     <NoWarn>$(NoWarn);1701;1702;1591</NoWarn>
   </PropertyGroup>

src/AutoMapper.Extensions.ExpressionMapping/MapperExtensions.cs

@@ -278,6 +278,33 @@ public static Dictionary<Type, Type> AddTypeMapping(this Dictionary<Type, Type>
             return typeMappings;
         }
 
+        /// <summary>
+        /// Replaces a type in the source expression with the corresponding destination type.
+        /// </summary>
+        /// <param name="typeMappings"></param>
+        /// <param name="sourceType"></param>
+        /// <returns></returns>
+        public static Type ReplaceType(this Dictionary<Type, Type> typeMappings, Type sourceType)
+        {
+            if (!sourceType.IsGenericType)
+            {
+                return typeMappings.TryGetValue(sourceType, out Type destType) ? destType : sourceType;
+            }
+            else
+            {
+                if (typeMappings.TryGetValue(sourceType, out Type destType))
+                    return destType;
+                else
+                    return sourceType.GetGenericTypeDefinition().MakeGenericType
+                    (
+                        sourceType
+                        .GetGenericArguments()
+                        .Select(type => typeMappings.ReplaceType(type))
+                        .ToArray()
+                    );
+            }
+        }
+
         private static Dictionary<Type, Type> AddTypeMappingsFromDelegates(this Dictionary<Type, Type> typeMappings, IConfigurationProvider configurationProvider, Type sourceType, Type destType)
         {
             if (typeMappings == null)

src/AutoMapper.Extensions.ExpressionMapping/XpressionMapperVisitor.cs

@@ -124,7 +124,7 @@ protected override Expression VisitLambda<T>(Expression<T> node)
         {
             var ex = this.Visit(node.Body);
 
-            var mapped = Expression.Lambda(ex, node.GetDestinationParameterExpressions(this.InfoDictionary, this.TypeMappings));
+            var mapped = Expression.Lambda(this.TypeMappings.ReplaceType(node.Type), ex, node.GetDestinationParameterExpressions(this.InfoDictionary, this.TypeMappings));
             this.TypeMappings.AddTypeMapping(ConfigurationProvider, node.Type, mapped.Type);
             return mapped;
         }
@@ -214,7 +214,7 @@ protected override Expression VisitMethodCall(MethodCallExpression node)
 
             //type args are the generic type args e.g. T1 and T2 MethodName<T1, T2>(method arguments);
             var typeArgsForNewMethod = node.Method.IsGenericMethod
-                ? node.Method.GetGenericArguments().Select(i => TypeMappings.ContainsKey(i) ? TypeMappings[i] : i).ToList()//not converting the type it is not in the typeMappings dictionary
+                ? node.Method.GetGenericArguments().Select(type => this.TypeMappings.ReplaceType(type)).ToList()//not converting the type it is not in the typeMappings dictionary
                 : null;
 
             ConvertTypesIfNecessary(node.Method.GetParameters(), listOfArgumentsForNewMethod, node.Method);

tests/AutoMapper.Extensions.ExpressionMapping.UnitTests/XpressionMapperTests.cs

@@ -469,6 +469,19 @@ public void Map_orderBy_thenBy_GroupBy_Select_expression()
             Assert.True(users[0].Count == 2);
         }
 
+        [Fact]
+        public void Map_orderBy_thenBy_GroupBy_SelectMany_expression()
+        {
+            //Arrange
+            Expression<Func<IQueryable<UserModel>, IQueryable<UserModel>>> grouped = q => q.OrderBy(s => s.Id).ThenBy(s => s.FullName).GroupBy(s => s.AgeInYears).SelectMany(grp => grp);
+
+            //Act
+            Expression<Func<IQueryable<User>, IQueryable<User>>> expMapped = mapper.MapExpression<Expression<Func<IQueryable<User>, IQueryable<User>>>>(grouped);
+            List<User> users = expMapped.Compile().Invoke(Users).ToList();
+
+            Assert.True(users.Count == 2);
+        }
+
         [Fact]
         public void Map_orderBy_thenBy_To_Dictionary_Select_expression()
         {